Crystalline polypropylene and molded object and film thereof

ABSTRACT

Provided is a crystalline polypropylene of which the 0° C. soluble content, α (% by weight), as measured through programmed-temperature fractionation and the molecular weight, Mp, for the peak in the molecular weight distribution curve as measured through gel permeation chromatography satisfy the relationship of the following formula (1): 
     
       
         α≦−0.42×ln( Mp )+7.3  (1), 
       
     
     and the melting point, Tm (° C.), as measured through differential scanning calorimetry and Mp satisfy the relationship of the following formula (2): 
     
       
           Tm&gt; 1.85×ln( Mp )+144.5  (2). 
       
     
     Also provided are moldings and films of the crystalline polypropylene. The crystalline polypropylene and its moldings and films are highly rigid and have good heat resistance and good scratch resistance.

TECHNICAL FIELD

The present invention relates to crystalline polypropylene and itsmoldings and films, precisely to crystalline polypropylene and itsmoldings and films which are rigid and have good heat resistance andgood scratch resistance.

BACKGROUND ART

Polypropylene resins have good heat resistance, good chemical resistanceand good electrical properties. In addition, they are rigid and havehigh tensile strength, good optical properties, and are easy to work.Therefore, they are used, for example, in injection molding, filmformation, sheet formation and blow molding. Moreover, as their specificgravity is low, they are widely used in various fields including, forexample, containers and wrapping materials. However, for someapplications, the properties of the resins are not always satisfactory,and use of the resins is often limited.

Of the properties of polypropylene noted above, its rigidity, heatresistance and scratch resistance are inferior to those of polystyreneand ABS resins. Therefore, for moldings which must be especially rigidand have good heat resistance, polypropylene can not be used. If it isdesired that polypropylene moldings have the same high rigidity and goodheat resistance as polystyrene or ABS resin moldings, their thicknessmust be made large. This means that thin polypropylene moldings aredifficult to produce and their production costs are high. For thesereasons, applications of polypropylene and polypropylene compositionscan not be further expanded. If polypropylene could be improved to havesatisfactory rigidity, chemical resistance, moldability, heat resistanceand hardness, it could be a substituent for polystyrene and ABS resinsand its applications could be expanded further. If so, in addition, thinmoldings of polypropylene could be produced. Such improvedpolypropylene, if obtained, would have the advantage of saving naturalresources and reducing the costs in producing its moldings.

In addition, when applied to the field of films, for example, forwrapping or packaging eatables or fibers, or for various sundries, etc.,the polypropylene films could exhibit good properties of high rigidityand good heat resistance with low molding shrinkage while they are wellextensible.

This being the situation, some techniques for increasing the rigidity ofcrystalline polypropylene are known. For example, one known method isthat of adding an organic nucleating agent, such as aluminiumpara-tert-butylbenzoate, 1,8-2,4-dibenzylidenesorbitol or sodium2,2-methylenebis(4,6-di-tert-butylphenyl) phosphate, to crystallinepolypropylene, and molding the resulting composition. However, themethod is expensive and is not economical. In addition, the method hasthe problem that the organic nucleating agent added to crystallinepolypropylene greatly lowers the surface gloss, the impact strength andthe tensile elongation of the polypropylene moldings. Another method forenhancing the rigidity of crystalline polypropylene is known, whichcomprises adding an inorganic filler such as talc, calcium carbonate orkaolin to crystalline polypropylene. In this method, however, theinorganic filler added detracts from the intrinsic characteristics ofcrystalline polypropylene its light weight and transparency. Inaddition, the method has the problem that the impact strength, thegloss, the tensile elongation and the workability of the polypropylenemoldings produced are poor.

In that situation, the object of the present invention is to provide anovel crystalline polypropylene and its moldings and films having theadvantages of high rigidity, good heat resistance and good scratchresistance. Precisely, the invention is to provide a novel crystallinepolypropylene and its moldings and films having the advantages of highflexural modulus, high tensile modulus, high heat deformationtemperature and high hardness.

DISCLOSURE OF THE INVENTION

We, the present inventors have done assiduous researches to attain theobject noted above, and, as a result, have found that the component ofpolypropylene which does not crystallize but remains dissolving in asolvent in its crystallization step (this component will be isotacticpolypropylene or a low-molecular-weight component) lowers the degree ofcrystallinity of the polymer, acting as a factor of retarding therigidity, the heat resistance and the scratch resistance of the polymer.We have further found that, when the amount of the soluble component ofpolypropylene, the melting point of the polymer as measured throughdifferential scanning calorimetry, and the molecular weight for the peakin the molecular weight distribution curve of the polymer as measuredthrough gel permeation chromatography (GPC) satisfy a specificrelationship therebetween, then the polymer, polypropylene could haveenhanced rigidity, heat resistance and scratch resistance and meets theobject of the invention. On the basis of these findings, we havecompleted the invention.

Specifically, the invention provides a novel crystalline polypropyleneand its moldings and films, which are as follows:

1. A crystalline polypropylene of which the 0° C. soluble content, α (%by weight), as measured through programmed-temperature fractionation andthe molecular weight, Mp, for the peak in the molecular weightdistribution curve as measured through GPC satisfy the relationshipgiven in the following formula (1):

 α≦−0.42×ln(Mp)+7.3  (1),

and the melting point, Tm (° C.), as measured through differentialscanning calorimetry and Mp satisfy the relationship given in thefollowing formula (2):

Tm>1.85×ln(Mp)+144.5  (2).

2. The crystalline polypropylene of above 1, of which the ratio of theweight-average molecular weight Mw to the number-average molecularweight Mn, Mw/Mn, as measured through GPC is at most 6.5.

3. The crystalline polypropylene of above 1 or 2, of which the intrinsicviscosity [η] as measured in a tetralin solvent at 135° C. falls between0.5 and 4.0 dl/g.

4. The crystalline polypropylene of any one of above 1 to 3, of whichthe molecular weight, Mp, for the peak in the molecular weightdistribution curve as measured through GPC is at least 10,000.

5. A molding of the crystalline polypropylene of any one of above 1 to4.

6. A film of the crystalline polypropylene of any one of above 1 to 4.

BEST MODES OF CARRYING OUT THE INVENTION

The crystalline polypropylene and its moldings and films of theinvention are described hereinunder.

1. Crystalline Polypropylene

Of the crystalline polypropylene of the invention, the 0° C. solublecontent, α (% by weight), as measured through programmed-temperaturefractionation and the molecular weight, Mp, for the peak in themolecular weight distribution curve as measured through GPC must satisfythe relationship given in the following formula (1):

α≦−0.42×ln(Mp)+7.3  (1).

Preferably, the two satisfy the following formula (3), and morepreferably the following formula (4):

α≦−0.42×ln(Mp)+6.8  (3)

α≦−0.42×ln(Mp)+6.3  (4).

If formula (1) is not satisfied, the rigidity of the crystallinepolypropylene is low, and is unfavorable.

Of the crystalline polypropylene of the invention, the 0° C. solublecontent, α (% by weight) is measured according to the following method.75 mg of the polymer to be tested is put into 10 ml of o-dichlorobenzeneat room temperature, and dissolved therein, stirring at 135 to 150° C.for 1 hour, to prepare a sample solution. 0.5 ml of the sample solutionis charged into a column at 135° C., and then gradually cooled to 0° C.at a cooling rate of 10° C./hr, whereby the polymer is crystallized onthe surface of the filler in the column. During the process, the amountof the polymer not crystallized but still remaining in solution ismeasured, and this indicates the 0° C. soluble content of the polymer.

Mp is obtained according to the following method.

This is calculated from the data of gel permeation chromatography (GPC)of the polymer. Precisely, 240 μl of a sample solution having a polymerconcentration of 0.1 (weight/volume (%)) in 1,2,4-trichlorobenzene(containing300 ppm of BHT) is applied to a mixed polystyrene gel column(for example, Tosoh's GMH6HT) at a flow rate of 1.0 ml/min at 145° C. toobtain the molecular weight distribution curve of the polymer. Themolecular weight for the peak of the curve is given by Mp. For thedetection, used is a differential refraction indicator (RI), for whichthe wavelength of light is 3.41 μm.

In addition, the melting point, Tm (° C.), as measured throughdifferential scanning calorimetry and Mp of the crystallinepolypropylene of the invention must satisfy the relationship given inthe following formula (2):

Tm>1.85×ln(Mp)+144.5  (2).

Preferably, the two satisfy the following formula (5):

Tm>1.85×ln(Mp)+145.0  (5).

If formula (2) is not satisfied, the heat resistance of the crystallinepolypropylene is low, and is unfavorable.

Tm (° C.) is obtained according to the following method.

Loaded in a differential scanning calorimeter, Model DSC-7 fromPerkin-Elmer, a polypropylene sample (10 mg±0.05 mg) is heated from roomtemperature up to 220° C. at a heating rate of 500° C./min, kept at thetemperature for 3 minutes, then cooled down to 50° C. at a cooling rateof −10° C./min, kept at the temperature for 3 minutes, and again heatedup to 190° C. at a heating rate of 10° C./min. In the heat cycle givinga curve for the melting profile of the sample, the peak appearing in thecurve after 150° C. in the second-stage heating step is read. Thisindicates the melting point, Tm of the sample.

In addition to the requirement as above, the crystalline polypropyleneof the invention is preferably such that the ratio of its weight-averagemolecular weight Mw to its number-average molecular weight Mn, Mw/Mn, asmeasured through GPC is at most 6.5. More preferably, the ratio is atmost 5.5. If the ratio is larger than 6.5, the elongation and the impactresistance of the polymer will be low.

And further, the crystalline polypropylene of the invention preferablyhas an intrinsic viscosity [η] falling between 0.5 and 4.0 dl/g, morepreferably between 0.5 and 3.0 dl/g, when measured in a tetralin solventat 135° C. If its intrinsic viscosity [η] is lower than 0.5 dl/g, thecrystalline polypropylene will have poor heat resistance. If higher than4.0 dl/g the rigidity of the crystalline polypropylene will be low.

Still further, Mp of the crystalline polypropylene of the invention ispreferably at least 10,000, more preferable at least 30,000, even morepreferably at least 50,000. If its Mp is smaller than 10,000, thecrystalline polypropylene will have poor heat resistance.

2. Method for Producing Crystalline Polypropylene

The crystalline polypropylene of the invention may be produced bypolymerizing propylene in the presence of a catalyst that comprises (A)a solid catalyst component prepared by contacting a magnesium compoundand a titanium compound with each other in the presence of an electrondonor compound and, if necessary, a silicon compound, at a temperaturefalling between 120° C. and 150° C., followed by washing the resultingproduct with an inert solvent at a temperature falling between 100° C.and 150° C., (B) an organic aluminium compound, and, if necessary, athird component (C) consisting of an electron donor compound.

Catalyst components, a method for preparing the catalyst, and a methodof polymerizing propylene are described below.

[I] Catalyst Components

(A) Solid Catalyst Component

The solid catalyst component comprises magnesium, titanium and anelectron donor, and is formed from (a) a magnesium compound, (b) atitanium compound, (c) an electron donor compound, and, if necessary,(d) a silicon compound, which are as follows:

(a) Magnesium Compound

The magnesium compound for use in the invention is not specificallydefined. Preferably used herein are magnesium compounds of a generalformula (I):

MgR¹R²  (I)

In formula (I), R¹ and R² each represent a hydrocarbon residue, a groupof OR³ (where R³ represents a hydrocarbon residue), or a halogen atom.More precisely, the hydrocarbon residue includes, for example, C₁₋₁₂alkyl, cycloalkyl, aryl and aralkyl groups. In the group OR³, R³includes, for example, C₁₋₁₂ alkyl, cycloalkyl, aryl and aralkyl groups.The halogen atom includes, for example, chlorine, bromine, iodine andfluorine atoms. R¹ and R² may be the same or different ones.

Specific examples of the magnesium compounds of formula (I) includealkylmagnesiums and arylmagnesiums such as dimethylmagnesium,diethylmagnesium, diisopropylmagnesium, dibutylmagnesium,dihexylmagnesium, dioctylmagnesium, ethylbutylmagnesium,diphenylmagnesium, dicyclohexylmagnesium, etc.; alkoxymagnesiums andaryloxymagnesiums such as dimethoxymagnesium, diethoxymagnesium,dipropoxymagnesium, dibutoxymagnesium, dihexyloxymagnesium,dioctoxymagnesium, diphenoxymagnesium, dicyclohexyloxymagnesium, etc.;alkylmagnesium halides and arylmagnesium halides such as ethylmagnesiumchloride, butylmagnesium chloride, hexylmagnesium chloride,isopropylmagnesium chloride, isobutylmagnesium chloride,t-butylmagnesium chloride, phenylmagnesium bromide, benzylmagnesiumchloride, ethylmagnesium bromide, butylmagnesium bromide,phenylmagnesium chloride, butylmagnesium iodide, etc.; alkoxymagnesiumhalides and aryloxymagnesium halides such as butoxymagnesium chloride,cyclohexyloxymagnesium chloride, phenoxymagnesium chloride,ethoxymagnesium bromide, butoxymagnesium bromide, ethoxymagnesiumiodide, etc.; magnesium halides such as magnesium chloride,magnesiumbromide, magnesium iodide, etc.

Of these magnesium compounds, preferred are magnesium halides,alkoxymagnesiums, alkylmagnesiums and alkylmagnesium halides, in view oftheir polymerization capability and stereospecificity.

The magnesium compounds noted above may be prepared from metal magnesiumor magnesium-containing compounds.

One example of producing the magnesium compounds comprises contacting ametal magnesium with a halogen and an alcohol.

The halogen includes iodine, chlorine, bromine and fluorine. Of those,preferred is iodine. The alcohol includes, for example, methanol,ethanol, propanol, butanol, cyclohexanol, octanol, etc.

Another example of producing the magnesium compounds comprisescontacting a magnesiumalkoxy compound of Mg(OR⁴)2 (where R⁴ represents ahydrocarbon residue having from 1 to 20 carbon atoms) with a halide.

The halide includes, for example, silicon tetrachloride, silicontetrabromide, tin tetrachloride, tin tetrabromide, hydrogen chloride,etc. Of those, preferred is silicon tetrachloride, in view of itspolymerization capability and stereospecificity. R⁴ includes, forexample, an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl,isobutyl, hexyl and octyl groups, etc.; a cyclohexyl group; an alkenylgroup such as allyl, propenyl and butenyl groups, etc.; an aryl groupsuch as phenyl, tolyl and xylyl groups, etc.; an aralkyl group such asphenethyl and 3-phenylpropyl groups, etc. Of those, especially preferredis an alkyl group having from 1 to 10 carbon atoms.

The magnesium compounds may be supported by a carrier; for example,silica, alumina, or polystyrene.

The magnesium compounds may be used either singly or as combined. Ifdesired, they may contain other elements such as halogens, e.g., iodine,as well as silicon, aluminium, etc., and may further contain electrondonors such as alcohols, ethers, esters, etc.

(b) Titanium Compound

The titanium compound for use in the invention is not specificallydefined. Preferably used herein are titanium compounds of a generalformula (II):

 TiX¹p(OR⁵)4−p  (II)

In formula (II), X¹ represents a halogen atom, and is preferably achlorine atom or a bromine atom, more preferably a chlorine atom. R⁵represents a hydrocarbon residue, which may be saturated or unsaturated,and may be linear, branched or cyclic. It may have hetero atoms such assulfur, nitrogen, oxygen, silicon, phosphorus and the like. Preferably,however, R⁵ is a hydrocarbon residue having from 1 to 10 carbon atoms,more preferably an alkyl, alkenyl, cycloalkenyl, aryl or aralkyl group,even more preferably a linear or branched alkyl group. A plurality of(OR⁵)'s, if any, may be the same or different ones. Specific examples ofR⁵include a methyl group, an ethyl group, an n-propyl group, anisopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group,an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octylgroup, an n-decyl group, an allyl group, a butenyl group, a cyclopentylgroup, a cyclohexyl group, a cyclohexenyl group, a phenyl group, a tolylgroup, a benzyl group, a phenethyl group, etc. p represents an integerof from 0 to 4.

Specific examples of the titanium compounds of formula (II) includetetraalkoxytitaniums such as tetramethoxytitanium, tetraethoxytitanium,tetra-n-propoxytitanium, tetraisopropoxytitanium,tetra-n-butoxytitanium, tetraisobutoxytitanium,tetracyclohexyloxytitanium, tetraphenoxytitanium, etc.; titaniumtetrahalides such as titanium tetrachloride, titanium tetrabromide,titanium tetraiodide, etc.; alkoxytitanium trihalides such asmethoxytitanium trichloride, ethoxytitanium trichloride, propoxytitaniumtrichloride, n-butoxytitanium trichloride, ethoxytitanium tribromide,etc.; dialkoxytitanium dihalides such as dimethoxytitanium dichloride,diethoxytitanium dichloride, diisopropoxytitanium dichloride,di-n-propoxytitanium dichloride, diethoxytitanium dibromide, etc.;trialkoxytitanium monohalides such as trimethoxytitanium chloride,triethoxytitanium chloride, triisopropoxytitanium chloride,tri-n-propoxytitanium chloride, tri-n-butoxytitanium chloride, etc. Ofthose, preferred are high-halogen titanium compounds in view of theirpolymerization capability. Especially preferred is titaniumtetrachloride. These titanium compounds may be used either singly or ascombined.

(c) Electron donor compound

The electron donor compound for use in the invention includesoxygen-containing electron donors, such as alcohols, phenols, ketones,aldehydes, esters of organic or inorganic acids, ethers, e.g.,monoethers, diethers, polyethers, etc.; and nitrogen-containing electrondonors such as ammonia, amines, nitriles, isocyanates, etc. Among theorganic acids, used are carboxylic acids, typically malonic acid.

Of these, preferred are esters of polycarboxylic acids, and morepreferred are esters of aromatic polycarboxylic acids. In view of theirpolymerization capability, especially preferred are monoesters and/ordiesters of aromatic dicarboxylic acids. Even more preferably, theorganic group in the ester segments of those esters should be a linear,branched or cyclic aliphatic hydrocarbon residue.

Concretely mentioned are dialkyl esters of dicarboxylic acids of, forexample, phthalic acid, naphthalene-1,2-dicarboxylic acid,naphthalene-2,3-dicarboxylic acid,5,6,7,8-tetrahydronaphthalene-1,2-dicarboxylic acid,5,6,7,8-tetrahydronaphthalene-2,3-dicarboxylic acid,indane-4,5-dicarboxylic acid and indane-5,6-dicarboxylic acid, in whichthe alkyl groups are any of methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, t-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl,3-methylbutyl, 1,1-dimethylpropyl, 1-methylpentyl, 2-methylpentyl,3-methypentyl, 4-methylpentyl, 1-ethylbutyl, 2-ethylbutyl, n-hexyl,cyclohexyl, n-heptyl, n-octyl, n-nonyl, 2-methylhexyl, 3-methylhexyl,4-methylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 2-methylpentyl,3-methylpentyl, 2-ethylpentyl and 3-ethylpentyl groups. Of these,preferred are diphthalates. Even more preferably, the organic group inthe ester segments of those esters should be a linear or branchedaliphatic hydrocarbon residue having at least 4 carbon atoms.

As specific examples of the preferred diphthalates, mentioned aredi-n-butyl phthalate, diisobutyl phthalate, di-n-heptyl phthalate, anddiethyl phthalate. These compounds may be used either singly or ascombined.

(d) Silicon Compound

In preparing the solid catalyst component, an additional ingredient (d)consisting of a silicon compound of the following general formula (III)is used where necessary, in addition to the ingredients (a), (b) and (c)noted above.

Si(OR⁶)qX²4−q  (III)

wherein R⁶ represents a hydrocarbon residue; X² represents a halogenatom; and q represents an integer of from 0 to 3.

Using the silicon compound in preparing the solid catalyst component ispreferred, as it often enhances the function and the stereospecificityof the catalyst and reduces the fine powder content found within thepolymer produced.

In formula (III), X² represents a halogen atom, and is preferably achlorine or bromine atom, more preferably a chlorine atom. R⁶ representsa hydrocarbon residue, which may be saturated or unsaturated, and may belinear, branched or cyclic. This may have hetero atoms such as sulfur,nitrogen, oxygen, silicon, phosphorus and the like. Preferably, however,R⁶ is a hydrocarbon residue having from 1 to 10 carbon atoms, morepreferably an alkyl, alkenyl, cycloalkenyl, aryl or aralkyl group. Aplurality of (—OR⁶)'s, if any, may be the same or different ones.Specific examples of R⁶ include a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group,an isobutyl group, an n-pentyl group, an n-hexyl group, an n-heptylgroup, an n-octyl group, an n-decyl group, an allyl group, a butenylgroup, a cyclopentyl group, a cyclohexyl group, a cyclohexenyl group, aphenyl group, a tolyl group, a benzyl group, a phenethyl group, etc. qrepresents an integer of from 0 to 3.

Specific examples of the silicon compounds of formula (III) includesilicon tetrachloride, methoxytrichlorosilane, dimethoxydichlorosilane,trimethoxychlorosilane, ethoxytrichlorosilane, diethoxydichlorosilane,triethoxychlorosilane, propoxytrichlorosilane, dipropoxydichlorosilane,tripropoxychlorosilane, etc. Of those, especially preferred is silicontetrachloride. These silicon compounds may be used either singly or ascombined.

(B) Organic Aluminium Compound

The organic aluminium compound (B) for use in producing the crystallinepolypropylene of the invention is not specifically defined. Preferablyused are organic aluminium compounds having any of alkyl groups, halogenatoms, hydrogen atoms and alkoxy groups, as well as aluminoxanes andtheir mixtures. Concretely mentioned are trialkylaluminiums such astrimethylaluminium, triethylaluminium, triisopropylaluminium,triisobutylaluminium, trioctylaluminium, etc.; dialkylaluminiummonochlorides such as diethylaluminium monochloride,diisopropylaluminium monochloride, diisobutylaluminium monochloride,dioctylaluminium monochloride, etc.; alkylaluminium sesqui-halides suchas ethylaluminium sesqui-chloride, etc.; linear aluminoxanes such asmethylaluminoxane, etc. Of those organic aluminium compounds, preferredare trialkylaluminiums having C₁₋₅ lower alkyl groups, and especiallypreferred are trimethylaluminium, triethylaluminium,triisopropylaluminium and triisobutylaluminium. The organic aluminiumcompounds may be used either singly or as combined.

(C) Third Component (Electron Donor Compound)

In preparing the polymerization catalyst to be used herein for producingthe crystalline polypropylene of the invention, used when necessary is(C) an electron donor compound. The electron donor compound (C) includesorganic silicon compounds with Si-O-C bonds, nitrogen-containingcompounds, phosphorus-containing compounds, and oxygen-containingcompounds. Of those, especially preferred are organic silicon compoundswith Si—O—C bonds, and also ethers and esters, in view of theirpolymerization capability and stereospecificity. More preferred areorganic silicon compounds with Si—O—C bonds.

Specific examples of the organic silicon compounds with Si—O—C bondsinclude tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane,tetraisobutoxysilane, trimethylmethoxysilane, trimethylethoxysilane,triethylmethoxysilane, triethylethoxysilane,ethylisopropyldimethoxysilane, propylisopropyldimethoxysilane,diisopropyldimethoxysilane, diisobutyldimethoxysilane,isopropylisobutyldimethoxysilane, di-t-butyldimethoxysilane,t-butylmethyldimethoxysilane, t-butylethyldimethoxysilane,t-butylpropyldimethoxysilane, t-butylisopropyldimethoxysilane,t-butylbutyldimethoxysilane, t-butylisobutyldimethoxysilane,t-butyl(s-butyl)dimethoxysilane, t-butylamyldimethoxysilane,t-butylhexyldimethoxysilane, t-butylheptyldimethoxysilane,t-butyloctyldimethoxysilane, t-butylnonyldimethoxysilane,t-butyldecyldimethoxysilane,t-butyl(3,3,3-trifluoromethylpropyl)dimethoxysilane,cyclohexylmethyldimethoxysilane, cyclohexylethyldimethoxysilane,cyclohexylpropyldimethoxysilane, cyclopentyl-t-butyldimethoxysilane,cyclohexyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane,dicyclohexyldimethoxysilane, bis(2-methylcyclopentyl)dimethoxysilane,bis(2,3-dimethylcyclopentyl)dimethoxysilane, diphenyldimethoxysilane,phenyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane,propyltrimethoxysilane, isopropyltrimethoxysilane,butyltrimethoxysilane, isobutyltrimethoxysilane,t-butyltrimethoxysilane, s-butyltrimethoxysilane, amyltrimethoxysilane,isoamyltrimethoxysilane, cyclopentyltrimethoxysilane,cyclohexyltrimethoxysilane, norbornyltrimethoxysilane,indenyltrimethoxysilane, 2-methylcyclopentyltrimethoxysilane,cyclopentyl(t-butoxy) dimethoxysilane, isopropyl (t-butoxy)dimethoxysilane, t-butyl(isobutoxy)dimethoxysilane,t-butyl(t-butoxy)dimethoxysilane, thexyltrimethoxysilane,thexylisopropoxydimethoxysilane, thexyl(t-butoxy)dimethoxysilane,thexylmethyldimethoxysilane, thexylethyldimethoxysilane,thexylisopropyldimethoxysilane, thexylcyclopentyldimethoxysilane,thexylmyristyldimethoxysilane, thexylcyclohexyldimethoxysilane, etc.

Also usable herein are silicon compounds of a general formula (IV):

wherein R⁷ to R⁹ each represent a hydrogen atom or a hydrocarbonresidue, and they may be the same or different, and may be bonded to theadjacent group to form a ring; R¹⁰ and R¹¹ each represent a hydrocarbonresidue, and they may be the same or different, and may be bonded to theadjacent group to form a ring; R¹² and R¹³ each represent an alkyl grouphaving from 1 to 20 carbon atoms, and they may be the same or different;m represents an integer of at least 2; and n represents an integer of atleast 2.

In formula (IV), concretely, R⁷ to R⁹ each may be a hydrogen atom; alinear hydrocarbon residue such as a methyl group, an ethyl group, ann-propyl group, etc.; a branched hydrocarbon residue such as anisopropyl group, an isobutyl group, a t-butyl group, a thexyl group,etc.; a saturated cyclic hydrocarbon residue such as a cyclobutyl group,a cyclopentyl group, a cyclohexyl group, etc.; or an unsaturated cyclichydrocarbon residue such as a phenyl group, a pentamethylphenyl group,etc. Of those, preferred are a hydrogen atom and C1-6 linear hydrocarbonresidues; and more preferred are a hydrogen atom, a methyl group, and anethyl group.

In formula (IV), R¹⁰ and R¹¹ each may be a linear hydrocarbon residuesuch as a methyl group, an ethyl group, an n-propyl group, etc.; abranched hydrocarbon residue such as an isopropyl group, an isobutylgroup, a t-butyl group, a thexyl group, etc.; a saturated cyclichydrocarbon residue such as a cyclobutyl group, a cyclopentyl group, acyclohexyl group, etc.; or an unsaturated cyclic hydrocarbon residuesuch as a phenyl group, a pentamethylphenyl group, etc. These R¹⁰ andR¹¹may be the same or different. Of the groups concretely mentioned,preferred are C1-6 linear hydrocarbon residues; and more preferred are amethyl group and an ethyl group.

In formula (IV), R¹² and R¹³ each maybe a linear or branched alkylgroup, such as a methyl group, an ethyl group, an n-propyl group, anisopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group,a t-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group,etc. These R¹² and R ¹³may be the same or different. Of the groupsconcretely mentioned, preferred are C1-6 linear hydrocarbon residues;and more preferred is a methyl group.

Preferred examples of the silicon compounds of formula (IV) areneopentyl-n-propyldimethoxysilane, neopentyl-n-butyldimethoxysilane,neopentyl-n-pentyldimethoxysilane, neopentyl-n-hexyldimethoxysilane,neopentyl-n-heptyldimethoxysilane, isobutyl-n-propyldimethoxysilane,isobutyl-n-butyldimethoxysilane, isobutyl-n-pentyldimethoxysilane,isobutyl-n-hexyldimethoxysilane, isobutyl-n-heptyldimethoxysilane,2-cyclohexylpropyl-n-propyldimethoxysilane,2-cyclohexylbutyl-n-propyldimethoxysilane,2-cyclohexylpentyl-n-propyldimethoxysilane,2-cyclohexylhexyl-n-propyldimethoxysilane,2-cyclohexylheptyl-n-propyldimethoxysilane,2-cyclopentylpropyl-n-propyldimethoxysilane,2-cyclopentylbutyl-n-propyldimethoxysilane,2-cyclopentylpentyl-n-propyldimethoxysilane,2-cyclopentylhexyl-n-propyldimethoxysilane,2-cyclopentylheptyl-n-propyldimethoxysilane,isopentyl-n-propyldimethoxysilane, isopentyl-n-butyldimethoxysilane,isopentyl-n-pentyldimethoxysilane, isopentyl-n-hexyldimethoxysilane,isopentyl-n-heptyldimethoxysilane, isopentylisobutyldimethoxysilane,isopentylneopentyldimethoxysilane, diisopentyldimethoxysilane,diisoheptyldimethoxysilane, diisohexyldimethoxysilane, etc. Of those,more preferred are neopentyl-n-propyldimethoxysilane,neopentyl-n-pentyldimethoxysilane, isopentylneopentyldimethoxysilane,diisopentyldimethoxysilane, diisoheptyldimethoxysilane,diisohexyldimethoxysilane; and even more preferred areneopentyl-n-pentyldimethoxysilane, and diisopentyldimethoxysilane.

The silicon compounds of formula (IV) may be produced by any method theproducer prefers. Typical processes for producing them are mentionedbelow.

In these processes, the starting compounds [1] are on the market, or maybe prepared through known alkylation or halogenation. The compounds [1]are subjected to the publicly known Grignard reaction to obtain theorganic silicon compounds of formula (IV).

The organic silicon compounds mentioned above maybe used either singlyor as combined.

Specific examples of the nitrogen-containing compounds include2,6-substituted piperidines such as 2,6-diisopropylpiperidine,2,6-diisopropyl-4-methylpiperidine,N-methyl-2,2,6,6-tetramethylpiperidine, etc.; 2,5-substituted azolidinessuch as 2,5-diisopropylazolidine, N-methyl-2,2,5,5-tetramethylazolidine,etc.; substituted methylenediamines such as N,N,N′,N′-tetramethylmethylenediamine, N,N,N′,N′-tetraethylmethylenediamine,etc.; substituted imidazolidines such as 1,3-dibenzylimidazolidine,1,3-dibenzyl-2-phenylimidazolidine, etc.

Specific examples of the phosphorus-containing compounds includephosphites such as triethyl phosphite, tri-n-propyl phosphite,triisopropyl phosphate, tri-n-butyl phosphite, triisobutyl phosphite,diethyl-n-butyl phosphite, diethylphenyl phosphite, etc.

Specific examples of the oxygen-containing compounds include2,6-substituted tetrahydrofurans such as2,2,6,6-tetramethyltetrahydrofuran, 2,2,6,6-tetraethyltetrahydrofuran,etc.; dimethoxymethane derivatives such as1,1-dimethoxy-2,3,4,5-tetrachlorocyclopentadiene, 9,9-dimethoxyfluorene,diphenyldimethoxymethane, etc.

[II] Preparation of Solid Catalyst Component

The solid catalyst component (A) noted above may be prepared by bringingthe magnesium compound (a), the titanium compound (b), the electrondonor (c) and, if necessary, the silicon compound (d) into contact witheach other in any known method, except for the temperature at which theyare contacted with each other. The order they are brought into contactis not specifically defined. For example, the components may be broughtinto contact with each other in an inert solvent such as a hydrocarbonsolvent, or they may be first diluted with an inert solvent such as ahydrocarbon solvent and then contacted with each other. The inertsolvent includes, for example, aliphatic hydrocarbons and alicyclichydrocarbons such as octane, decane, ethylcyclohexane, etc., and alsotheir mixtures.

The amount of the titanium compound to be used may be generally from 0.5to 100 mols, preferably from 1 to 50 mols, relative to 1 mol ofmagnesium of the magnesium compound. If the molar ratio of the twooversteps the defined range, the catalyst function will be poor. Theamount of the electron donor to be used may be generally from 0.01 to 10mols, preferably from 0.05 to 1.0 mol, relative to 1 mol of magnesium ofthe magnesium compound. If the molar ratio of the two oversteps thedefined range, the catalyst function and stereospecificity will be poor.The amount of the silicon compound, if used, may be generally from 0.001to 100 mols, preferably from 0.005 to 5.0 mols, relative to 1 mol ofmagnesium of the magnesium compound. If the molar ratio of the twooversteps the defined range, the silicon compound used will notsatisfactorily realize its potentiality to improve the catalyst activityand stereospecificity. If so, in addition, the amount of fine powdercontained within the polymer produced will increase.

To bring about contact between the components (a) to (d), they are allmixed and heated at a temperature falling between 120 and 150° C.,preferably between 125 and 140° C. If the temperature of contactoversteps the defined range, the catalyst function and stereospecificitywill be poor. Under the conditions, they are brought into contact witheach other generally for a period of from 1 minute to 24 hours,preferably from 10 minutes to 6 hours. The pressure applied duringcontact may vary, depending on the type of the solvent, if used, and onthe contact temperature, but generally falls between 0 and 50 kg/cm²G,preferably between 0 and 10 kg/cm²G. During the operation for bringingthem into contact with each other, it is desirable to stir the system soas to ensure uniform contact and enhance the efficiency of contact.

Also desirably, the titanium compound is contacted at least twice withthe magnesium compound that serves as a catalyst carrier, to allow themagnesium compound to satisfactorily carry out its purpose.

Where a solvent is used in the contact operation, its amount may begenerally at most 5000 ml, but preferably from 10 to 1000 ml, relativeto one mol of the titanium compound. If the ratio oversteps the definedrange, uniform contact can not be attained and the contact efficiencywill be low.

The solid catalyst component produced as a result of the contactoperation noted above is washed with an inert solvent at a temperaturefalling between 100 and 150° C., preferably between 120 and 140° C. Ifthe washing temperature oversteps the defined range, the catalystfunction and stereospecificity cannot be sufficient. The inert solventcan be, for example, aliphatic hydrocarbons such as octane, decane,etc.; alicyclic hydrocarbons such as methylcyclohexane,ethylcyclohexane, etc.; aromatic hydrocarbons such as toluene, xylene,etc.; halogenohydrocarbons such as tetrachloroethane,chlorofluorohydrocarbons, etc.; and their mixtures. Of those, preferredare aliphatic hydrocarbons.

The washing method is not specifically defined; however, preferred isdecantation or filtration. The amount of the inert solvent to be used,the washing time, and how many times the washing operation is repeatedare not also specifically defined. In general, for example, the amountof the solvent to be used may fall between 100 and 100000 ml, preferablybetween 1000 and 50000 ml, relative to 1 mol of the magnesium compound,and the washing time may fall between 1 minute and 24 hours, preferablybetween 10 minutes and 6 hours. If the ratio oversteps the definedrange, the product cannot be washed satisfactorily.

The pressure for the washing operation varies, depending on the type ofthe solvent used and the washing temperature, but may fall generallybetween 0 and 50 kg/cm²G, preferably between 0 and 10 kg/cm²G. Duringthe washing operation, it is desirable to stir the system so as toensure uniform washing and enhance the washing efficiency. The resultingsolid catalyst component may be stored in dry, or in an inert solventsuch as a hydrocarbon solvent.

[III] Polymerization

The amount of the catalyst to be used in producing the crystallinepolypropylene of the invention is not specifically defined. For example,the solid catalyst component (A) may be used in an amount of generallyfrom 0.00005 to 1 mmol, in terms of the titanium atom content thereof,relative to one liter of the reaction system. Regarding the amount ofthe component (B), organic aluminium compound to be used, the atomicratio of aluminium/titanium may fall generally between 1 and 1000, butpreferably between 10 and 500. If the atomic ratio oversteps the definedrange, the catalyst function will be poor. Regarding the amount of thethird component (C), electron donor compound such as an organic siliconcompound, if used, the molar ratio of electron donor compound (C)/organic aluminium compound (B) may fall generally between 0.001 and5.0, but preferably between 0.01 and 2.0, more preferably between 0.05and 1.0. If the molar ratio oversteps the defined range, the catalystwill not exhibit satisfactory activity and stereospecificity. However,if the catalyst is subjected to prepolymerization and the thuspre-treated catalyst is used, the amount of the third component (C) maybe reduced to be smaller than the defined range.

In the invention, if desired, before the polymerization in the presenceof the catalyst to produce the intended crystalline polypropylene,olefin prepolymerization in the presence of the same may be performed.This is for realizing high catalytic function and high stereospecificityof the catalyst and for improving the powdery morphology of the polymerproduced. In that case, an olefin is first prepolymerized in thepresence of the catalyst as prepared by mixing the solid catalystcomponent (A), the organic aluminium compound (B) and, if necessary, theelectron donor compound (C) in a predetermined ratio, generally at atemperature falling between 1 and 100° C. under a pressure fallingbetween normal pressure and 50 kg/cm²G or so, and thereafter propyleneis polymerized in the presence of the catalyst and the prepolymer havingbeen formed in the previous prepolymerization step.

For the prepolymerization, preferably used are α-olefins of a generalformula (V):

R¹⁴—CH═CH₂  (V)

In formula (V), R¹⁴ represents a hydrogen atom or a hydrocarbon residue.The hydrocarbon residue may be saturated or unsaturated. The olefinsconcretely include ethylene, propylene, 1-butene, 1-pentene, 1-hexene,1-heptene, 1-octene, 1-decene, 3-methyl-1-pentene, 4-methyl-l-pentene,vinylcyclohexane, butadiene, isoprene, piperylene, etc. These olefinsmay be used either singly or as combined. Of the olefins noted above,especially preferred are ethylene and propylene.

The mode of polymerization to produce the crystalline polypropylene ofthe invention is not specifically defined, and may be among of thefollowing: solution polymerization, slurry polymerization, vapor-phasepolymerization, and bulk polymerization. Any of batch polymerization andcontinuous polymerization may apply to the polymerization mode, andtwo-stage or multi-stage polymerization under different conditions alsomay apply thereto.

Regarding the reaction conditions, the polymerization pressure is notspecifically defined and may fall generally between atmospheric pressureand 80 kg/cm²G, but preferably between 2 and 50 kg/cm²G; and thepolymerization temperature may fall generally between 0 and 200° C., butpreferably between 20 and 90° C., more preferably between 40 and 90° C.,in view of the polymerization efficiency. The polymerization timevaries, depending on the temperature at which the starting propylene ispolymerized, and therefore cannot be unconditionally defined. Ingeneral, however, the polymerization time may fall between 5 minutes and20 hours, preferably between 10 minutes and 10 hours or so.

The molecular weight of the polymers to be produced in that manner maybecontrolled by adding a chain transfer agent, preferably hydrogen to thereaction system. If desired, the polymerization may be effected in thepresence of an inert gas such as nitrogen or the like.

If desired, the starting propylene may be polymerized in two or morestages under different polymerization conditions.

Regarding the catalyst components for use in the invention, thecomponents (A), (B) and (C) may be previously mixed in a predeterminedratio and brought into contact with each other, and, immediately afterthe preparation of the catalyst in that manner, propylene may bepolymerized in the presence of the catalyst; or after the catalyst thusprepared has been aged for 0.2 to 3 hours or so, propylene may bepolymerized in the presence of it. The catalyst components may be usedafter having been suspended in an inert solvent or propylene.

In the invention, the post-treatment after polymerization may beeffected in any ordinary manner. For example, the powdery polymer asproduced in vapor-phase polymerization is taken out of thepolymerization reactor, and a nitrogen stream may be introducedthereinto so as to remove the non-reacted olefin from the polymer. Ifdesired, the polymer may be pelletized through an extruder. In thiscase, a small amount of water, alcohol or the like may be added to thepolymer so as to completely render the catalyst inactive. The polymer asproduced in bulk polymerization is taken out of the polymerizationreactor, the non-reacted monomer is completely removed from it, and theresulting polymer may be pelletized.

3. Moldings

The moldings of the invention are formed from the crystallinepolypropylene. They include, for example, interior finishings for cars,housings for electric and electronic appliances for household use, filmsfor wrapping or packaging eatables, sheets, etc. To produce themoldings, the crystalline polypropylene may be molded, for example,through injection molding, compression molding, injection compressionmolding, gas-assisted injection molding, extrusion molding, blow moldingor the like.

To form the moldings of the invention from the crystallinepolypropylene, if desired, surface-modifying additives such asantistatic agents, defogging agents, etc.; as well as other variousknown additives such as antiblocking agents, antioxidants,weather-proofing agents, heat stabilizers, neutralizing agents,lubricants, nucleating agents, colorants, organic or inorganic fillersand others may be added to the crystalline polypropylene, and theresulting polymer composition may be molded.

4. Films

The films of the invention may be formed from the crystallinepolypropylene. The method for forming the films is not specificallydefined, and includes, for example, ordinary compression sheeting,extrusion sheeting, blow sheeting, etc. The films of the invention maybe or may not be oriented. If biaxially oriented, the films may beformed under the following sheeting conditions.

<1> Condition for sheeting:

Polymer temperature: 200 to 300° C.

Chill roll temperature: not higher than 50° C.

<2> Condition for orientation in machine direction:

Draw ratio: 3 to 7 times the original length.

Temperature: 130 to 160° C.

<3> Condition for orientation in transverse direction:

Draw ratio: 6 to 12 times the original width.

Temperature: 150 to 175° C.

If desired, the films may be subjected to surface treatment, therebyhaving increased surface energy or having polar surfaces. For example,the surface treatment includes corona discharging, chromate treatment,exposure to flame, exposure to hot air, exposure to ozone or UV rays,and also surface roughening through sand blasting or in solvents, etc.

To form the films of the invention from the crystalline polypropylene,also if desired, surface-modifying additives such as antistatic agents,defogging agents, etc.; as well as other various known additives such asantiblocking agents, antioxidants, weather-proofing agents, heatstabilizers, neutralizing agents, lubricants, nucleating agents,colorants, organic or inorganic fillers and others may be added to thecrystalline polypropylene, and the resulting polymer composition may besheeted.

EXAMPLES

The invention is described in more detail with reference to thefollowing Examples.

Example 1

(Preparation of Solid Catalyst Component)

A 5-liter three-neck flask equipped with a stirrer was purged withnitrogen gas, and 160 g of diethoxymagnesium and then 600 ml ofdewatered octane were put thereinto in that order. After the mixture washeated at 40° C., 24 ml of silicon tetrachloride was added thereto andstirred for 20 minutes. Then, 16 ml of dibutyl phthalate was addedthereto. The resulting solution was further heated up to 80° C., and 770ml of titanium tetrachloride was dropwise added thereto through adropping funnel. The inner temperature was kept at 125° C., and thecompounds were catalytically reacted for 2 hours. The resulting productwas fully washed with dewatered octane at 125° C. 1220 ml of titaniumtetrachloride was added thereto, and the inner temperature was kept at125° C. Under the condition, the compounds were catalytically reactedfor further 2 hours. After this, the product was fully washed withdewatered octane at 125° C. Thus was prepared a solid component

(Prepolymerization)

A 1-liter three-neck flask equipped with a stirrer was purged withnitrogen gas, and 48 g of the solid component [A] and then 400 ml ofdewatered heptane were put thereinto in that order. This was heated at40° C., and 2.0 ml of triethylaluminium and 6.3 ml ofdiisopentyldimethoxysilane were added thereto. Propylene was introducedinto the flask under normal pressure and reacted for 2 hours. Afterthis, the solid component was fully washed with dewatered heptane. Thuswas prepared a catalyst component to be used herein.

(Polymerization)

A 10-liter stainless autoclave equipped with a stirrer was fully driedand purged with nitrogen, and 6 liters of dewatered heptane was putthereinto. While stirring, this was heated up to 80° C. To thethus-heated heptane, added were 40.0 mmols of triethylaluminium, then5.0 mmols of dicyclopentyldimethoxysilane, and 0.1 mmols, in terms ofTi, of the solid catalyst component prepared previously, in that order.Then, hydrogen was introduced thereinto to have a hydrogen pressure of2.5 kg/cm²G, and then propylene was introduced thereinto until there wasa total pressure of 8.0 kg/cm²G. After the total pressure reached 8.0kg/cm²G, the monomer was polymerized for 1 hour. Next, the reactionsystem was cooled and degassed, and the reaction product was taken outof the autoclave. The solvent was removed from the reaction product bythe use of an evaporator, and the resulting product was dried in vacuumto obtain polypropylene.

(Preparation of Samples for Identifying the Structural Characteristicsand the Mechanical Properties of the Polymer)

To the polypropylene powder obtained herein, added were 1500 ppm ofcalcium stearate (from Nippon Oils and Fats) and 500 ppm of DHT-4A (fromKyowa Chemical) both serving as a neutralizing agent, 750 ppm of P-EPQ(from Clarient) and 1500 ppm of Irganox 1010 (from Ciba SpecialityChemicals) both serving as an antioxidant, and 2000 ppm of PTBBA-A1(from Dai-Nippon Ink Chemical) serving as a nucleating agent, and theywere well mixed. The resulting mixture was melted, kneaded andpelletized into pellets, through a 20 mm single-screw melt extruder. Apart of the pellets were subjected to a predetermined test foridentifying the structural characteristics of the polymer. The remainingpellets were formed into test pieces through pressing or injectionmolding, and the test pieces were tested for their mechanicalproperties.

(Test Pieces for Mechanical Properties)

(1) Test Pieces for Tensile Modulus, Formed Through Pressing

The polymer pellets were melt-pressed into a plate having a thickness of1 mm, and test pieces were blanked out of the plate. For themelt-pressing, the polymer pellets were melted at 220° C. for 3 minutes,then pressed under a pressure of 50 Kgf/cm² for 2 minutes, cooled to 30°C., and again pressed under a pressure of 50 Kgf/cm² for 5 minutes ormore.

(2) Test Pieces Formed Through Injection Molding

Using an injection molding machine, IS100FIII Model (from ToshibaMachine), the polymer pellets were molded into test pieces, for whichthe temperature of the polymer pellets being molded was 200° C. and thetemperature of the mold was 45° C.

(Identification of the Structural Characteristics and the MechanicalProperties of the Polymer)

(1) Intrinsic Viscosity [η]

The polymer was dissolved in tetralin, and its viscosity was measured at135° C.

(2) 0° C. Soluble Content and Peak Temperature in Elution Curve inProgrammed-temperature Fractionation

The polymer polypropylene produced through polymerization was subjectedto programmed-temperature fractionation to identify its structuralcharacteristics. The sample was prepared as follows: 75 mg of thepolymer to be tested was put into 10 ml of o-dichlorobenzene at roomtemperature, and dissolved therein, stirring at 135 to 150° C. for 1hour, to prepare a sample solution. 0.5 ml of the sample solution wascharged into a column at 135° C., and then gradually cooled to 0° C. ata cooling rate of 10° C./hr, whereby the polymer was crystallized on thesurface of the filler existing in the column. During the process, theamount of the polymer not crystallized but still remaining in solutionwas measured, this indicating the 0° C. soluble content of the polymer.

(3) Molecular Weight Mp for the Peak in the Molecular WeightDistribution Curve, Weight-average Molecular Weight Mw andNumber-average Molecular Weight Mn of the Polymer Measured Through GPC

Mp, Mw and Mn of the polymer were calculated from the data of gelpermeation chromatography (GPC) of the polymer. Precisely, 240 μl of asample solution having a polymer concentration of 0.1 (weight/volume(%)) in 1,2,4-trichlorobenzene (containing 300 ppm of BHT) was appliedto a mixed polystyrene gel column (for example, Tosoh's GMH6HT) at aflow rate of 1.0 ml/min at 145° C. to obtain the molecular weightdistribution curve of the polymer. The molecular weight Mp for the peakof the curve, the weight-average molecular weight Mw, and thenumber-average molecular weight Mn of the polymer were obtained from thedata measured. For the detection, used was a differential refractionindicator (RI), for which the wavelength of light was 3.41 μm.

(4) Melting Point, Tm (° C.)

Loaded in a differential scanning calorimeter, Model DSC-7 fromPerkin-Elmer, the polymer polypropylene (10 mg±0.05 mg) was heated fromroom temperature up to 220° C. at a heating rate of 500° C./min, kept atthe temperature for 3minutes, then cooled down to 50° C. at a coolingrate of −10° C./min, kept at the temperature for 3 minutes, and againheated up to 190° C. at a heating rate of 10° C./min. In the heat cyclegiving a curve for the melting profile of the polymer, the peakappearing in the curve after 150° C. in the second-stage heating stepwas read, this indicating the melting point, Tm of the polymer.

(5) Test of Test Pieces of Pressed Plate

A plate was formed from the polymer through melt-pressing, and testpieces were blanked out of the plate. The test pieces were testedaccording to JIS-K7113.

(6) Test of Test Pieces Formed Through Injection Molding

Test pieces formed from the polymer through injection molding weretested for their tensile modulus, flexural modulus, heat deformationtemperature (HDT) and Rockwell hardness (HR, in R scale), according toJIS-K7113, JIS-K7203, JIS-K7207 and JIS-K7202, respectively.

The data obtained in the tests are shown in Table 1.

Example 2

The same process as in Example 1 was repeated, except that the degree ofhydrogen introduction into the polymerization system was changed to 1.2kg/cm²G. The test data are in Table 1.

Example 3

The same process as in Example 1 was repeated, except that the degree ofhydrogen introduction into the polymerization system was changed to 0.8kg/cm²G. The test data are in Table 1.

Example 4

The same process as in Example 1 was repeated, except that the degree ofhydrogen introduction into the polymerization system was changed to 0.5kg/cm²G. The test data are in Table 1.

Example 5

The polymer of Example 3 was sheeted into a bi-oriented film. Thepolymer temperature was 260° C.; the chill roll temperature was 30° C.;the temperature for MD orientation was 140° C.; the draw ratio for MDorientation was 4.6 times the original length; the temperature for TDorientation was 166° C.; and the draw ratio for TD orientation was 9.2times the original width. The bi-oriented film was subjected to atensile test according to JIS-K7127, and its tensile modulus was 6500MPa. The film was subjected to a water vapor permeation test accordingto the Method B of JIS-K7129, and the water vapor permeation ratethrough the film was 3.70 g/m².

Comparative Example 1

(Preparation of Solid Catalyst Component)

A 5-liter three-neck flask equipped with a stirrer was purged withnitrogen gas, and 160 g of diethoxymagnesium and then 600 ml ofdewatered heptane were put thereinto in that order. After the mixturewas heated at 40° C., 24 ml of silicon tetrachloride was added theretoand stirred for 20 minutes. Then, 25 ml of diethyl phthalate was addedthereto. The resulting solution was further heated up to 80° C., and 470ml of titanium tetrachloride was dropwise added thereto through adropping funnel. The inner temperature was kept at 110° C., and thecompounds were catalytically reacted for 2 hours. The resulting productwas fully washed with dewatered heptane at 90° C. 770 ml of titaniumtetrachloride was added thereto, and the inner temperature was kept at110° C. Under the condition, the compounds were catalytically reactedfor further 2 hours. After this, the product was fully washed withdewatered heptane at 90° C. Thus was prepared a solid component [B].

(Prepolymerization)

A 1-liter three-neck flask equipped with a stirrer was purged withnitrogen gas, and 48 g of the solid component [B] and then 400 ml ofdewatered heptane were put thereinto in that order. This was kept at 10°C., and 2.7 ml of triethylaluminium and 2.0 ml ofcyclohexylmethyldimethoxysilane were added thereto. Propylene wasintroduced into the flask under normal pressure and reacted for 2 hours.After this, the solid component was fully washed with dewatered heptane.Thus was prepared a catalyst component to be used herein.

(Polymerization)

A 10-liter stainless autoclave equipped with a stirrer was fully driedand purged with nitrogen, and 6 liters of dewatered heptane was putthereinto. While stirring, this was heated up to 80° C. To thethus-heated heptane, added were 40.0 mmols of triethylaluminium, then5.0 mmols of cyclohexylmethyldimethoxysilane, and 0.1 mmols, in terms ofTi, of the solid catalyst component prepared previously, in that order.Then, hydrogen was introduced thereinto to have a hydrogen pressure of3.0 kg/cm²G, and then propylene was introduced thereinto to have a totalpressure of 8.0 kg/cm²G. After the total pressure reached 8.0 kg/cm²G,the monomer was polymerized for 1 hour. Next, the reaction system wascooled and degassed, and the reaction product was taken out of theautoclave. The solvent was removed from the reaction product by the useof an evaporator, and the resulting product was dried in vacuum toobtain polypropylene. The polymer was tested, and the data are in Table2.

Comparative Example 2

The same process as in Comparative Example 1 was repeated, except thatthe degree of hydrogen introduction into the polymerization system waschanged to 0.5 kg/cm²G. In this, in addition, the polypropylene powderobtained through polymerization was once dried, then heptane was addedthereto to reach 200 g/liter, the resulting mixture was stirred at 83°C. for 1 hour, and thereafter the supernatant separated above themixture was removed while still kept at the elevated temperature, andfinally the residue was dried in vacuum to obtain polypropylene. Thepolymer was tested, and the data are in Table 2.

Comparative Example 3

The same process as in Comparative Example 1 was repeated, except thatthe degree of hydrogen introduction into the polymerization system waschanged to 0.2 kg/cm²G. The test data are in Table 2.

Comparative Example 4

The same process as in Comparative Example 1 was repeated, except thatthe degree of hydrogen introduction into the polymerization system waschanged to 0.07 kg/cm²G. The test data are in Table 2.

Comparative Example 5

The same process as in Comparative Example 1 was repeated, except thatthe degree of hydrogen introduction into the polymerization system waschanged to 0.01 kg/cm²G. The test data are in Table 2.

Comparative Example 6

The polymer of Comparative Example 4 was sheeted simply into abi-oriented film. The bi-oriented film was subjected to a tensile testaccording to JIS-K7127, and its tensile modulus was 5800 MPa. The filmwas subjected to a water vapor permeation test according to the Method Bof JIS-K7129, and the water vapor permeation rate through the film was4.64 g/m².

TABLE 1 Example 1 Example 2 Example 3 Example 4 0° C. Soluble Content1.30 0.90 0.93 0.91 (wt. %) Mp 82200 113200 169400 512000 Value of RightSide of 2.55 2.41 2.24 1.78 Formula (1) Melting Point (Tm) 166.4 168.2167.9 170.2 (° C.) Value of Right Side of 165.4 166.0 166.8 168.8Formula (2) [η] 1.10 1.50 1.85 2.85 Tensile Modulus <1> 2690 2600 25402510 (MPa) Tensile Modulus <2> 2100 2050 2020 2020 (MPa) FlexuralModulus (MPa) 2100 2030 1990 2010 Heat Deformation 64 62 62 62Temperature (° C.) Rockwell Hardness 117 114 115 114 Tensile Modulus<1>: Samples produced through pressing. Tensile Modulus <2>: Samplesproduced through injection molding.

TABLE 2 Comparative Comparative Comparative Comparative ComparativeExample 1 Example 2 Example 3 Example 4 Example 5 0° C. Soluble Content(wt. %) 3.16 1.65 2.49 2.25 2.21 Mp 69300 86900 102200 190000 534500Value of Right Side of 2.62 2.52 2.46 2.19 1.76 Formula (1) MeltingPoint (Tm) (° C.) 163.4 164.9 165.8 166.5 168.5 Value of Right Side of165.1 165.5 165.8 167.0 168.9 Formula (2) [η] 0.84 1.06 1.46 1.90 2.76Tensile Modulus <1> (MPa) 2480 2540 2330 2200 2080 Tensile Modulus <2>(MPa) 1880 1910 1800 1810 1830 Flexural Modulus (Mpa) 1820 1830 16901700 1730 Heat Deformation 63 61 60 59 58 Temperature (° C.) RockwellHardness 114 114 112 111 110 Tensile Modulus <1>: Samples producedthrough pressing. Tensile Modulus <2>: Samples produced throughinjection molding.

INDUSTRIAL APPLICABILITY

The novel crystalline polypropylene of the invention is highly rigid,and can be formed into thin and lightweight moldings. Therefore, theinvention has the advantages of saving natural resources and realizinghigh productivity. In addition, since the moldings of the invention arehighly rigid and have good heat resistance, they can be substituents forconventional polystyrene and ABS resin moldings. Further, the films ofthe invention are highly rigid and have good heat a resistance, they arefavorable to those for wrapping and packaging eatables, etc.

What is claimed is:
 1. A crystalline polypropylene having a 0° C.soluble content α (percent by weight) as measured throughprogrammed-temperature fractionation and a molecular weight Mp, for thepeak in the molecular weight distribution curve as measured through gelpermeation chromatography which satisfy the relationship in the formula:(1)  α≦−0.42×ln(Mp)+7.3  (1) and having a melting point Tm (° C.), asmeasured through differential scanning calorimetry, which with Mpsatisfy the relationship in the formula (2): Tm>1.85×ln(Mp)+144.5  (2)wherein a ratio of a weight-average molecular weight Mw to anumber-average molecular Mn, Mw/Mn, as measured through gel permeationchromatography, is at most 6.5.
 2. The crystalline polypropylene ofclaim 1, having an intrinsic viscosity [η] as measured in tetralinsolvent at 135° C. which is between 0.5 and 4.0 dl/g.
 3. The crystallinepolypropylene of claim 1, having a molecular weight Mp, for the peak inthe molecular weight distribution curve as measured through gelpermeation chromatography, of at least 10,000.
 4. The crystallinepolypropylene of claim 1, wherein a and Mp satisfy the relationship inthe formula: α≦−0.42×ln(Mp)+6.8.
 5. The crystalline polypropylene ofclaim 4, wherein a and Mp satisfy the relationship in the formula:α≦−0.42×ln(Mp)+6.3.
 6. The crystalline polypropylene of claim 1, whereinTm and Mp satisfy the relationship in the formula: Tm>1.85×Ln(Mp)+145.0.7. The crystalline polypropylene of claim 1, wherein Mw/Mn is at most5.5.
 8. The crystalline polypropylene of claim 2, wherein the intrinsicviscosity [η] is between 0.5 and 3.0 dl/g.
 9. The crystallinepolypropylene of claim 3, wherein Mp is at least 30,000.
 10. Thecrystalline polypropylene of claim 9, wherein Mp is at least 50,000. 11.A molding of the crystalline polypropylene of claim
 1. 12. The moldingof claim 11, which is an interior finishing for a car.
 13. The moldingof claim 11, which is a housing for an electric appliance.
 14. A film ofthe crystalline polypropylene of claim
 1. 15. The film of claim 14,which is biaxially oriented.
 16. The film of claim 14, which is surfacetreated by corona discharge, chromate treatment, flame exposure, hotair-exposure, ozone or UV-exposure, sand blasting or solvent treatment.